1. Field of the Invention
This invention relates to a metering device in a single lens reflex camera for measuring light passed through the picture-taking objective lens of the camera, and more particularly to a TTL metering device which has a light-sensing element and a jump-up mirror partly provided with an area through which light may be transmitted (hereinafter referred to as the light-transmitting area) so that the light passed from the picture-taking objective lens through the light-transmitting area may be directed to the light-sensing element to effect metering.
In conventional TTL metering devices of this type, an auxiliary mirror comprising a small plane mirror or a small curved mirror has been used to cause the light passed from the picture-taking objective lens through the light-transmitting area to be directed to the light-sensing element. However, in order that the metering range may be expanded, it has been necessary to enlarge the auxiliary mirror or to provide a large-diametered image forming lens in the metering optical system leading from the auxiliary mirror to the light-sensing element. This has in turn led to an increased space requirement and consequent larger size and increased weight of the camera. In addition, the larger size of the auxiliary mirror has increased the weight of the movable portion of the camera during shutter release.